CZ2012919A3 - Process for preparing oriented thin layers of hexagonal ferrites - Google Patents

Abstract

A process for preparing oriented thin layers of Y-type hexagonal ferrite on monocrystalline substrates by liquid phase deposition using sols, precursors based on inorganic salts, salts of organic acids, or alkoxides in a suitable solvent, upon application of a layer of hexagonal ferrite of the Y type SrTiO.sub.3.n (111) hexagonal ferrite type M layer of defined thickness, which undergoes, by controlled crystallization under given conditions of temperature, time and heating rate, transformation from a continuous layer into a discontinuous layer formed of isolated islands of crystalline nature, having an epitaxial relationship to the substrate structure. Due to the chemical similarity of the M phase and the ferrite phase Y, and due to the structural similarity of the M phase and the ferrite phase Y, the formation of an oriented layer of hexagonal ferrite type Y is possible.

Description

Process for preparing oriented thin layers of hexagonal ferrite

Technical field

The present invention relates to a process for the preparation of hexagonal ferrite layers by the liquid phase deposition method on monocrystalline substrates using a seed layer which allows the formation of an oriented phase.

BACKGROUND OF THE INVENTION

UPV201400027453

Hexagonal ferrites form both an important and extensive family of oxides containing Fe ³⁺ as the main metal cation, both structurally and in practical use. Based on the structure usually described by the sequence of basic structural blocks (S block (Me ²⁺ Fe 4 O 8, where Me means a divalent metal ion), R block [(Ba, Sr) Fe 60n] ² ', and T block [(Ba, Sr 2Fe80i ₄ ] [1]), hexagonal ferrites are divided into several groups: type M [(Ba, Sr) Fei20i9, spatial group 3 P6 ₃ / mmc], type W [(Ba, Sr) Me ₂ Fei ₆ O ₂ 7, group g. P6 ₃ / mmc], type X [(Ba, Sr) ₂ Me2Fe ₂₈ O ₄₆ , group R3m], type Y [(Ba, Sr) 2Me ₂ Fei2O22, group R-3m], type Z [ (Ba, Sr) ₃ Me ₂ Fe ₂ O ₄ i, group P6 ₃ / mmc] and type U [(Ba, Sr) ₄ Me ₂ Fe ₃₆ 06o, group R-3m] [1] material of permanent magnets [2,3], magnetic recording media [4,5], or microwave elements in the field of mobile communication [6-10].

The multi-ferroic materials are characterized by the coexistence of at least two types of ferro-like properties spontaneously ordered, such as electrical polarization P, magnetization M, or deformation. * \ [11]. It has been shown that by the links between the spontaneously ordered quantities, ' ¹ ', (characterized by the value of the coefficient of the respective linear effect), these arrangements can be manipulated with one another. E.g. by means of the phenomenon known as magnetoelectric (ME) effect (consisting of induction of magnetic (electric) polarization in material by external electric (magnetic) field) it is possible to influence magnetic domains in material with spontaneously arranged electric polarization and magnetization (in magnetoelectric multiferico) electric field or vice versa ferroelectric domains by magnetic field [8]. E.g. currently, high current densities that overheat components must be used for writing to Magnetic Random Access Memory (MRAMs), which makes it impossible to design MRAMs with high integration. If magnetoelectric coupling could be used in ME multi -eroids, it would be possible to easily influence the magnetic domains by the external electric field and to increase integration. Theoretically, it would be possible to replace the current system of two-bit computer logic with four-bit logic (both electric polarization and magnetization with possible states of jaf orientation). Therefore, the greatest expectations for the future application of ME multiferoics are associated with the control of the magnetic state of multiferoics through the external electric field usable in the field of recording media, magnetic field detection based on the phenomenon of "cxchange bias coupling" magnetically hard antiferromagnetics in ferro / antiferromagnetic multilayers) and in electron spin technologies for storing, transmitting and processing information - spintronics [12],

The key requirements for the applicability of ME multiferoics in these applications is (i) reaching a working temperature close to room temperature and (ii) the possibility of implementing these materials in the form of thin films in technologies commonly used in the semiconductor industry (CMOS technology Complementary Metal-Oxide-Semiconductor). One of the thin film preparation methods used in the semiconductor industry is Chemical Solution Depositon (CSD), which uses a chemical solution of metal precursors as a starting system to form an oxide structure by a sol-gel process and subsequent crystallization [13]. By mid-2012, the magnetoelectric effect observed at room temperature was also observed for the following hexagonal ferrites: SrCo ₂ Ti ₂ Fe ₈ O 19, Ba ^ Sr ^ Z ^ Fe ^ C ^, BaSrAlCoZnFenO ₂ 2, (Ba, Sr) ₂ Zn ₂ (Fe, al) i2O22, Ba Mg2Fei2O22 _2, R 3 C ₂ Fe24O4i Sr ₂ Co ₄ Fe360 _least about [14] the materials were studied mostly in the form of single crystals or sintered ceramics.

As of mid-2012, only three articles were published describing the preparation of thin films of • non-M hexagonal ferrites (in all three cases of Y type [15-17]). In the work [15] »· · the authors have prepared thin layers of Ba ₂ Zn ₂ Fe ₂ O 22 by PLD method on single crystals * · 4 '' Α12θ3 (001) using ZnO as a seed layer. Due to the different volatility of Ba and Zn was; ”'; demanding optimization and compensation of Ba losses must be made by using chemical J · · and · / · '* targets. composition different from the target. Subsequently, they received oriented phases of phase Y, no direct evidence of the existence of an epitaxial relationship was provided. In the work [16], a modified method of “soft” chemistry (called “polymeric precursor method”) based on an aqueous solution of inorganic salts and citric acid was used. Using dip-coating deposition, thin layers of Ba ₂ Zn ₂ Fe ₁₂ O ₂ containing ZnFe ₂ O ₄ magnetic spinel as impurity were prepared on metallic silver substrates. The layers showed preferential orientation with the c-axis perpendicular to the plane of the substrate, with no evidence of the existence of an epitaxial relationship. The same method was used by the same authors in the work [17] for the preparation of thin layers of Ba2Co2Fei ₂ 0 ₂ 2 on metal substrates (Ag, Au and Pt) by the dipcoating method. No experimental evidence of the existence of the epitaxial relationship of the prepared oriented layers was provided, the results of the work were also patented [18],

The following factors are considered to be important factors for the success of oriented / epitaxial layers: (i) choice of substrate material (with appropriate thermal stability, high chemical stability, similar crystallographic structure and low lattice misfits), (ii) finding deposition and crystallization conditions (temperature, time, rise time). The reasons for the difficulties associated with the preparation of higher-grade hexagonal ferrites in the form of thin films are the following three negative circumstances: (i) it is very difficult to obtain a commercial support with a structure, symmetry and chemical composition close to hexagonal ferrites; (ii) while the base ferrite of M ((Basra) Fei ₂ 0i9) starts to crystallize at temperatures around 5 ° (Yc crystallization phase Y type requires it to temperatures higher than lOOOfC. At these temperatures have been changes in the chemical composition of the ferrite in the form of thin (iii) Due to the structural complexity and sometimes high number of metal ions in the ME ferrite structure, it is very difficult to optimize the conditions of preparation of the starting material for the deposition of thin films.

SUMMARY OF THE INVENTION

These problems of preparation of oriented layers of hexagonal ferrite Y-type are solved by the proposed method of their preparation, which consists in

1) a single crystal SrTiO3 (ST) with a cutting orientation of the surface (111) is used as a substrate.

This commercially available material is suitable for the following reasons:

(i) value of lattice misfit (Δ between SrTiO3 (III) and Ba2- _x Sr _x Zn2Fei2O22 phase is -6.1 |% calculated according to the formula:

A = (p2a (substr} -atferite)! 42a (substrtyx 100, (ii) symmetry similarities (hexagonal symmetry of O ² 'and Sr ² * ions in plane 111; ·, · »structure of ST and O ² ' ions in structure Ba2- _x Sr _x Zn2Fei2O22), and '* -i · · (iii) partial chemical similarity (both chemical structures contain Sr ² * ions).

2 / the liquid phase deposition method (CSD) is used as the deposition method, based on the liquid: '' chemical solution of suitable metal precursors (solo) followed by heat treatment · '·';

Causing crystallization of the desired oxidic phase. Any of the techniques commonly used in CSD may be used as a method of applying the sols: dip-coating, spin-coating, spray-coating. · Firstly, a layer of ferrite type M is deposited with (BaSr) (FeAl) i20i9, (BaSr) (FeGa) i20i9, which are isostructured with SrFei20i9, preferably with a composition (Bai. _x Sr _x) Fei20i9. The composition of the M layer (expressed by parameter x) is preferably selected so that the ratio of Ba: Sr in the M layer coincides with the ratio of Ba: Sr in the Y layer. The M layer (hereinafter referred to as the seed layer) is deposited under such conditions the metal concentration in the sol and the characteristic deposition rate (expressed, for example, for spin-coating as rpm), allowing the formation of a layer with equivalent thickness of 5 to 50 nm. 20 to 40 nm. As used herein, equivalent thickness refers to the thickness of the M phase layer as measured by a profilometer on a sample formed from ten M phase layers deposited under germ phase preparation conditions and converted to a single layer thickness. E.g. values of the equivalent germ layer thickness between 20-40 nm prepared from the sol of Example 2 (alkoxide pathway) are achieved under Fe 0 concentration conditions _; 25 - 0 _; 5 mol / dm ³ and spin-coater rotation speed 3000

3 <, rpm.

The embryonic layer plays the role of a chemical barrier and a structural pattern in the proposed method of preparing oriented hexagonal ferrite layers.

a. substantially lower temperature crystallization M phase relative to the phase of Y (t _Cry st (M) ~ 450PC t _Cryst (Y) ^-1 and

1100 ° C) epitaxial layer of M ferrite is formed without appreciable changes in its chemical composition due to eg reaction with substrate

b. similarities in the chemical composition of M ferrite (eg BaFe ^ O ^) with Y-type ferrites serve as a chemical barrier to prevent changes in the Y-phase chemical composition that may occur due to the reaction between the top ferrite layer and the ST substrate material

c. The structural similarity of M ferrite to Y-type ferrites is facilitated by crystallization of the Y phase

d. values of lattice misfit Δ between SrTiChO 11 structure and M phase structure (Ast-m ⁼ 6.1%) and between M and Y structures of ferrite ((Δ _Μ -γ = 0.45%) form a suitable structural pattern and facilitate formation of oriented Y phase ferrite

4) subsequently a sol layer with a composition corresponding to one of the type Y ferrite, which may have a phase composition exhibiting a magneto-electric phenomenon (see above, hereinafter referred to as the "ME ferrite layer"), is applied to form a 50-100 nm thick layer; by pyrolysis and crystallization forms a continuous layer of ferrite. This step is preferably carried out repeatedly in order to prepare a layer of the desired thickness. After each cycle of deposition, controlled drying and pyrolysis, the crystallization of the ferrite phase is carried out by vigorously heating to 1100 ° C for several minutes. After the last cycle, crystallization is performed in the same manner for several tens of minutes.

. The following groups of substances may advantageously be used as starting precursors: transition alkoxides

• alkaline earth metals and metals, transition metal and alkaline earth metals hexanoates, β * · · · · - transition metal and alkaline earth metal diketones, alkali metal acetates, nitrates and »· I«

A. transition metal chlorides, always dissolved in suitable solvents.

As a suitable solvent for the transition metal and alkaline earth metal alkoxides and / or ethylhexanoates of the precursor system, preference may be given to alcohols and / or ether alcohols with lower and / or medium carbon chain lengths (C2 to C5).

As a modifier in the case of salts formed predominantly of transition metal and alkaline earth metal alkoxides, preferably monoethanolamine, diethanolamine, triethanolamine, or acetylacetone added in the desired amount may be used.

As a suitable solvent for the nitrate and metal chloride precursor system, a simple polyhydric alcohol (e.g. ethylene glycol, propanediol, butanediol) can be advantageously used in admixture with water and a simple alcohol.

The crystallization of the ferrite phase is preferably achieved by placing the pyrolyzed layer sample in a conventional laboratory furnace preheated to the desired temperature, or using a Rapid Control Annealing (RTA) device.

X

The AFM (Atomic Force Microscopy) method has been found to deposit and crystallize the seed layer as described above to initially disintegrate the initially continuous pyrolyzed layer to form the isolated islets / crystallites as documented on G $ br. I. These islands consist of isolated hexagonal-shaped crystals and have a specific crystallographic orientation with respect to the c-axis substrate of the SrFe-Oig phase perpendicular to the plane of the substrate as shown in [23].

X-ray diffraction (XRD) methods have shown that the application of the ME ferrite layer and its crystallization as described above produces a strong preferred orientation of the Y phase, which can be described by (00L) y // (III) st [100 ] γ // [2-1 -1] st or [100] γ // [1 1-2] st (also refer to Qbr. 2, 3, 4). Strong anisotropy of crystallographic orientation was confirmed by measuring the magnetic properties of the ST / M / Y layer (in Qbr. 5). At a suitable (low) thickness of the seed layer, both its magnetic properties and diffraction methods have shown that its content in the final material is below the detection limit.

Advantages of the process for preparing oriented hexagonal ferrite layers according to the invention are in particular

a. the ability to simply induce the growth of an oriented layer of hexagonal ferrite type

Y on single crystal SrTiO3 supports (11).

AND·

b. the technological simplicity of low investment costs for coating;

equipment, using available starting materials, in the possibility of applying layers in an open * · * atmosphere. ".

t »· ·

c. variability in the ability to easily control the process parameters relevant to the formation of layers (stoichiometric composition, solo hydrodynamic parameters, heat treatment scenario), and the possibility of a very rapid adaptation of the method to modify the process already known. , or the development of the preparation of the newly discovered ME ferrites, in the future.

t

d. CSD adaptability to thin film preparation methods used in integrated circuit technology.

Literature:

[1] H.P.J. Wijn, Chapter 10 in The Landolt-Boemstein Database, Group III Condensed Matter,

Vol.4b: Part B (eds. K Hellerge, AM Hellerge, Springer Verlag, Germany)) 547 [2] JP / 2010061403, TDK CORP Japan [3] JP / 2002000996, NEOMAX CO LTD, Japan [4] EP / 1441332 , FUJIFILM CORP, Japan [5] EP / 0962919, FUJIPHOTO FILM CO. LTD, Japan [6] WO / 2012/103020, SKYWORKS SOLUTIONS, INC. USA [7] WO / 2012063913, TODA KOGYO CORPORATION Japan [8] WO / 2007/148438, Hitachi Metals, Ltd. Japan [9] WO / 2006/064839, Hitachi Metals, Ltd. Japan [10] US / 6623879, Toda Kogyo Corp., Japan [11] N.A. Spaldin and M. Fiebig: The renaissance of magnetoelectric multiferroics, Science 309, 391 (2005) [12] R. Ramesh, N.A. Spaldin, Multiferroics: Progress and Prospects in Thin Films, Nature Materials, 6 (2007) 21 [13] R. W. Schwartz, Chem. Mater. 9 (1997) 2325 [14] T. Kimura, Magnetoelectric hexaferrites, Annu. Roar. Condens. Matter. Phys. 3 (2012) 93. [15] H. Kim, J.S. Horwitz, et. al., J. Vac. Sci. Technol. A 17, (1999) 3111 [16] T. Fujii, A. Harran, et. al., J. Mater. Res. 16, (2001) 2471 [17] K. Komatsu, M. Nakanishi et al., J. Magn. Magn. Mater. 272-276, (2004) el831 [18] US / 7,141,311, Japan Science and Technology Agency (Saitama, JP); EP / 1340716, JAPAN

SCIENCE & TECH CORP, JP [19] F.F. Lange, Science 273 (1996) 903. [20] K.T. Miller, F.F. Lange, J. Mater. Res. 6 (1991) 2387, "[21] J.H. Kim, F.F. Lange, J. Mater. Res. 14 (1999) 1626.f. [22] R.W. Schwarz, P.G. Clem, et al., J. Am. Ceram. Soc., 82 (1999) 2359; 23 [23] J. Bursik, I. Drbohlav, et al., J. Solid State Chem. 84, (2011) 3085. · »9 · * 99 a» t »« »** · ** ♦ f 9 9 9

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BRIEF DESCRIPTION OF THE DRAWINGS

Giant. 1: scheme of the final product - a layer of ferrite Y on a SrTiO3 (III) substrate with a germ layer of ferrite M applied.

Giant. 2: AFM measurement and profile scans (corresponding to the color line in the AFM image) of a ferrite M phase (SrFe ^ Oig) seed layer deposited on a SrTiO3 (III) substrate by spin-coating and crystallized at 110 ° C by vigorous heating. Values r.m.s. (rootmean square) gives the effective value of the surface roughness. The disintegration of the originally continuous layer is evident into a discontinuous layer consisting of islets of hexagonal-shaped crystallites and dimensional parameters deductible from the profile scan.

Giant. 3: X-ray diffraction (XRD) recording by a theta-theta scan method, measured on a BaSrZnCoAlFenO22 thin film, with a Bao ^ Sro → Fe ^ OiQ seed layer deposited on a SrTiO3 (III) substrate by spin-coating, and crystallized at 100fC. The data show a high degree of preferential orientation of phase Y on the SrTiO3 (11) substrate - only the 001 order reflections are evident.

Giant. 4: Full Width in the Haif of Maximum (FWHM) obtained from diffraction patterns of omega scans (rocking curves) measured on planes 0027 on a thin layer of hexagonal ferrite Bao.5Sri.5Zn2Fei2022 deposited on a support. _t SrTiO3 (L 11), the germ layer SrFe OIG. The data allow semi-quantitative evaluation of the degree of π.

, 1 »14« preferred orientation. The dependency is seen that the optimum conditions (maximum level '* ⁴ Y orientation phase at the minimum possible thickness of the nucleation layer M phase) is about 40 nm thick M phase. . * '** · «· · · In the picture below is an example of an omega curve measured on the Y phase of reflection 0027 along with the curve of the.: *.

«· <

• «experimental data by Gaussian function.

Giant. 5: X-ray diffraction (XRD) recording by phi scan method measured on a layer of hexagonal ferrite Bao.5Sri.5Zn2Fei2022 deposited on a SrTiO3 support (III), with a SrFei20i9 seed layer. The coincidence of the positions of the individual maxima found for the substrate and the phases M and Y shows that the ferrite phases are in epitaxial relation to the structure of the substrate, which can be described in the notation of "ideal orientation" (hkl) // (h'kT), [uvw] // [u'v'w '] by the following relationships: (001) m, y // (111) sieve3, [1 00] m, y // [2- 1 -1] srTiO3 and (001) m, y // (1 1 l) srTi03, [100] m, y // [1L-2] srTi03 ·

Giant. 6: Record of magnetic hysteresis curves measured at room temperature on a thin layer of Ba2Zn2FenO22 deposited on a SrTiO3 (III) substrate with a BaFei20i9 seed layer in perpendicular and longitudinal orientation of the external magnetic field. The figure shows a significant magnetic anisotropy of the Y-ferrite layer.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Sr germ layer (FeAl) and ₂ 0i ₉ ME Bao layer ₍₅ Sri _{(5 Zn2} AlFe _t i0 ₂₂ based precursor salts of inorganic and / or organic acid salts.

.AND. Preparation of germ layer:

0.00165 molX strontium nitrate, Sr (NO3) ₂ , 0.01 aluminum nitrate, A1 (NO3) 3-9H ₂ O and 0.01 ferric nitrate, Fe (NO3) 3-9H ₂ O were under stirring and heating To 75 ° C, dissolve your 80 mL of mixed solvent prepared by mixing distilled water, ethylene glycol and ethanol (1: 2: 2 by volume) in a 250 mL Erlenmayer capped cap for about 6 hours. After complete dissolution, the volume of the solution was made up to 100 ml with the above solvent and stored in a sealed container at room temperature. The sol was then spun-coated onto a SrTiO3 support (11) using a 500 nm PTFE filter syringe. A speed of 3000 rpm was used for 30 sec. The gel layer sample was dried at 110 ° C for 10 min in a conventional laboratory oven, and then pyrolyzed on a hot plate at 35 ° C for 5-10 minutes. Pyrolyzed. *: A sample on a Al ₂ O 3 ceramic boat was placed directly in a laboratory oven heated to 10000C; Annealing at this temperature for 5 minutes h ^ 4. Final annealing was carried out at 1100 ° C for 8 hours. All steps of the layer preparation took place in an open atmosphere.

1 * ’I 1 .B. preparation of ME layer:

* * * ·· 0.0017 molX barium acetate, BaCCh, 0.0051 mol <strontium acetate, SrCCh, 0.0374 mol ferric ethyl hexanoate, (Fe (OOCCH (CH ₂ CH 3) CH ₂ CH ₂ CH ₂ CH 3) 3 0.0034 molt (ethylhexanoate ···· aluminum, (A1 (OOCCH (CH ₂ CH 3) CH ₂ CH ₂ CH ₂ CH 3) 3 and 0.0068 moles <zinc ethylhexanoate,> * t ♦ '(Zn (OOCCH (CH ₂ CH 3) CH ₂ CH ₂ CH ₂ CH 3) 2) your 80 ml of mixed solvent prepared by mixing 1: 1 isopropyl alcohol and acetic acid to this solvent was added monoethanolamine (MEA) as a modifier in an amount of 0.0068 molg (Rm = n (MEA / n (Sr + Ba) = 2) n - number moljj). dissolution was effected with stirring at 40i ° ^C in Erlenmeyer vessel of 250 ml equipped with a cap for 6 hours. after complete dissolution, the volume of the solution adjusted to volume of 100 ml with the above solvent and Storage at room The sol was then injected at room temperature Sprayers equipped with a PTFE filter with a pore size of 500 nm were applied by spin-coating technique to a SrTiO ₃ (11) substrate with a deposited and crystallized seed layer. A speed of 3000 rpm was used for 30 sec. The gel layer sample was dried at 110 ° C for 10 min in a laboratory oven, and then pyrolyzed on a hot plate at 350 ° C for 5-10 minutes. The pyrolyzed specimen on an AI2O3 ceramic boat was placed directly in a laboratory oven heated to 1100 ° C and *

Annealing at this temperature for 5 minutes. Final annealing was carried out at 1100 ° C for 8 hours. All steps of the layer preparation took place in an open atmosphere.

Example 2

Germ layer (BaSrjFe ^ Oig, ME layer BaSrZnCoAlFenO22, alkoxide-based precursors.

2.A. germ layer preparation:

0] 0017 mol methoxyethoxide barium Ba (OCH2CH2OCH3) 2, 0.0017 Molko methoxyethoxide strontium Sr _(OCH2 CH2OCH3) 2, 0 _t 04 mole isobutoxide ferric, Fe (OCH 2 CH (CH 3) 2) 3 were added while stirring heating dissolved in about 80 mL of absolute isobutanol. Binding and mixing of the precursors were carried out by box booths under a dried nitrogen atmosphere. Dissolution was carried out in a 250 ml Erlenmeyer flask equipped with a reflux condenser, under a nitrogen atmosphere at 80 ° C, for 6 hours. After complete dissolution and cooling of the solution to room temperature, diethanolamine (DEA) was added as modifier in an amount of 0.0434 molK (RM = n (DEA) / n (Sr + Ba + Fe) = 1, n - moles Q) and the solution was heated. and stirred for 2 hours at 80 DEG C. After cooling, the solution was made up to a total volume of 100 ml with isobutanol and stored in a desiccator at room temperature in a 1001 ml flask fitted with a ground glass stopper. The mixing and collecting operations were carried out under a dry nitrogen atmosphere in a dry box. The sol was injected using a syringe equipped with a PTFE filter with a 500 nm pore size.

Spin-coating techniques on a SrTiCl2 substrate 111). A speed of 3000 rpm was used for 30 ‘• * * sec. The gel layer sample was dried at 11 ° C for 10 min in an oven, and then pyrolyzed on a preheated hot plate at 35 ° C for 5-10 minutes. Pyrolyzed pattern on a boat. ..

of Al 2 O 3 ceramics was directly placed in a laboratory oven heated to 110 ° C and calcined at this temperature; · · · ‘4« · »for 8 hours.

2.B. preparation of ME layer:

0.005 mol $ (barium methoxyethoxide, Ba (OCH 2 CH 2 OCH 3) 2, 0.005 moles strontium methoxyethoxide, Sr (OCH 2 CH 2 OCH 3) 2, 0.005 mol (aluminum isobutoxide, A1 (OCH 2 CH (CH 3) 2) 3, 0.005 2, 0.005 mol of zinc ethyl hexanoate, (Zn (OOCCH (CH ₂ CH 3) CH ₂ CH ₂ CH ₂ CH 3) 2 and 0.055 moles of ferric isobutoxide, Fe (OCH 2 CH (CH 3) 2) 3 were dissolved with your 80 ml of absolute isobutanol. The dissolution was carried out in a 250 ml Erlenmeyer flask equipped with a reflux condenser, under a protective nitrogen atmosphere, at 80 ° C for 6 hours, after complete dissolution and cooling the solution to room temperature. diethanolamine (DEA) was added to the solution in an amount of 0.08 moles ((RM = n (DEA) / n (Sr + Ba + Zn 'X))

TCo + Fe) = 1, η - number of mol (K) and the solution was heated and stirred for 2 hours at 80 ° C. After cooling, the solution was made up to a total volume of 100 ml with isobutanol a

Án stored in a desiccator at room temperature, in a 1001 ml flask fitted with a ground-glass stopper. The mixing and collecting operations for the syringe were carried out under a nitrogen-protected nitrogen atmosphere. The sol was then spun-coated onto a SrTiO3 (III) with a deposited and crystallized seed layer using a syringe equipped with a 500 nm PTFE filter syringe. A speed of 3000 rpm was used for sec. The gel layer sample was dried at 11 ° C for 10 min in an oven, and then pyrolyzed to a <10 ° C preheated hot plate at 350 ° C for 5 minutes. The pyrolyzed specimen on an Al2O3 ceramic boat was directly placed in a laboratory oven heated to 1100 ° C and calcined at this temperature for 5 minutes. This deposition-drying-pyrrolysis-crystallization cycle was repeated to increase the final layer thickness (BaSr) (ZnCo) of AlFenO22. Typically, 10 cycles were sufficient to achieve a final thickness of 1000 nm. Crystallization after the last cycle was carried out at 1100PC for 4 hours. The deposition, drying and crystallization of the layer took place in an open atmosphere.

Industrial applicability

.. ·. Ekonom,: · ,, · This cost-effective and technologically simple way of preparing oriented "

.... thin films of hexagonal ferrite type Y can be used in existing electronic devices * »; * ;; using electromagnetic radiation in the radio frequency range 1 GHz to 300 GHz (GSM, satellite * I · ·· communication and navigation, GPS, civil and military radar technology), requiring electrically nonconductive. microwave materials with low dielectric losses; or leading to a substantial improvement of these types of microwave devices in the case of successful implementation of ME elements in these devices due to the possibility of dual (electric / magnetic field) tuning of their power.

^ JosefBurší ky

Radomír Kuželž

Claims (14)

PATENT CLAIMS A process for producing oriented hexagonal ferrite layers, characterized in that a sol prepared from a type M phase solution of inorganic or metallo-organic precursors having a metal ion composition corresponding to a stoichiometry (Mel) is deposited on a monocrystalline SrTiCh with cut orientation (111). (Me2) i2019, where Mel consists of Ba or Sr or Pb or a mixture thereof, Me2 consists of Fe or Al or Ga or a mixture thereof and the concentration of Me2 in the solution for type M phase is 0.05 to 0.4 mol / l , the gel layer of the type M phase from the deposited sol is dried, hydrolyzed and subsequently calcined, on this obtained crystallized seed layer from the ferrite phase type M is deposited a sol from the solution for the type Y phase from inorganic or metallo-organic precursors with metal ions composition corresponding to stoichiometry (Mel) 2 (Me3) 2 (Me2) 12O22, wherein Me3 consists of Zn or Co or Fe or a mixture thereof and the concentration of Me2 in the solution for the phase of type Y is 0.5 to 0.7 mol / l, the gel layer of the type Y deposited on the crystallized ferrite phase seed layer of type M is dried, hydrolyzed and subsequently calcined to obtain crystallized. í »ferrite phase type Y ...‘ t * »·. > «• · * ♦ Method according to claim 1, characterized in that the solution for the M ... ♦ t has a composition corresponding to the stoichiometry of metal ions (Bai. _x Sr _x) Me2FenOi9, where ^»1 * stoichiometric coefficient x can be any value in the interval from 0 to 1 inclusive '· extreme values. ^J liti * · fit · <<<I The production method according to claim 1, characterized in that the solution for the type Y phase has a metal ion composition corresponding to a stoichiometry (Ba 2 _x Sr _x ) (Me 3) 2 Me 2 PhenO 22, wherein the stoichiometric coefficient x can be any value in the interval 0 to 1.5. including extreme values. The production method according to claim 2, characterized in that the solution for the M-type phase has a metal ion composition corresponding to a stoichiometry (Ba 1 _x Sr _x ) of Fe 2 O 19. The method of claim 3, wherein the Y-phase solution has a metal ion composition corresponding to a stoichiometry (Ba 2 _x Sr _x ) Zn ₂ Fe ₂ O 22. 11 '. A process according to claim 1 or 2 or 3 or 4 or 5, characterized in that the concentration of Me2 in the solution for the type M phase is 0.1 to 0.2 mol / l. The production method according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that the sol is applied by spin-coating or dip-coating or spray-coating techniques. 8. The process of claim 7 wherein the sol is deposited at 2000 to 3000 rpm. The production method according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that the deposited gel layer is dried at 11 ° C for 10 minutes and subsequently pyrolyzed at a temperature of 350 to 45 ° C. ° C for 5 to 10 min. The method of claim 10 wherein the pyrolyzed type M phase layer is exposed to 1100 ° C for 1 to 24 hours with a sharp temperature rise of about 500 ° C / minute. * The method of claim 10, wherein the pyrolyzed phase layer The M-type is exposed to 1100 ° C for 4 to 8 hours. > í · · ·> H 9 · & A method according to claim 9 or 10 or 11, characterized in that the pyrolyzed type Y phase layer is exposed to 1100 ° C for 2 to 5 minutes. _{with a} sharp temperature rise of about 500 ° C / minute. 3 * »* ' -> “·» The method of claim 9 or 10 or 11 or 12, wherein the last pyrolyzed type Y phase layer is exposed to a temperature of 1100 ° C for 1 to 12 hours. 14. The method of claim 13 wherein the last pyrolyzed type Y phase layer is exposed to 1100 [deg.] C for 2 to 6 hours.